DeInterlacer V1.2 Ė by Daniel Kuhn
This document is available in english and german
This is just another one of these programs, born to fulfil a special need of a
friend. This time he had grabbed still images from his camcorder, but he had problems with the interlacing.
Those camcorders record half pictures (every second scanline) and put two of them together if
you want to have a still image. This works quite well, but he discovered
- A constant horizontal offset
When you were turning yourself while taking the video, the second half might be
- A constant vertical offset
When you made movements an up or downwards, the lines are shifted between the
- A nonconstant horizontal error
When you turn the camera, the top might have more or less offset than the
So I needed to write a program to work on all those. I didnít find one online, so
here it is. Enjoy, and have fun. As always: I donít take any responsibility for
what this software may do with your pictures.
Remember: Nothing is loss-free. Using this program to rework your images will crop some
pixels at the borders. Since the image wonít increase in size, you move some
pixels outside the viewing area. I decided that doesnít matter, since the
information at the border would not be complete anyway.
How to use it
I will explain on the image I included for testing purposes (Nice figures, huh?).
It shows all three errors. In my experience its best to start with the last
modification and work yourself up to the first. It might need some finetuning
between the first two (or all three) to get the best result.
Click "Load" and load your image. It has to be a Bitmap (BMP) and is limited to
some usual color depths. I had no problems with that, if you have just try to
convert your image to something standards (supported are 8, 16, 24 or 32 bit)
- Correct vertical mistakes
Try to use negative numbers first. You will see, that the ghost images divert. So itís
the wrong direction. If you turn it up a little, it is getting better. Turn it
to the place, where you think the two images fit best.
- Different horizontal offset Tip/Bottom
notice that there is a offset thatís different from top to bottom? Try to
remove it, so the vertical lines that should be identical are parallel to each
- Global horizontal offset
Now fix the uppermost value, so that no more offset exists. You should see the
lines in order. Of course, this image isnít sharp Ėyour image would usually not
be, too. This may take some modification with the other parameters to get all
- Final steps
If you want to know whether you dound the best values for this image, the correct adjustment is
Ė5 / 10 / 2 . You still see some distortion on the vertical line in the
background. That shows the limitation of this quite easy approach: It just
moves pixels, it does not correct mistakes. Some pixels are always lost using
|V1.0|| - ||Initial release|
|V1.1|| - ||Sorry, but I donít remember the changes|
|V1.2|| - ||Bugfix: Some images made the program crash while trying to read them. (Thanks to Michael Protzen for reporting this bug)|